Two stage electrostatic precipitators are composed of two sections, a charging section and a collection section. The charging section uses ionizer wires to impart a positive charge to the incoming smoke, fume and dust particles. The charged particles are then drawn into a secondary electric field where they are collected on a series of metal plates. Then, the electrostatic precipitators re-circulate clean air into the general airstream.
Over time, the collector section metal plates become coated with the contaminants captured by the air cleaner. Eventually, the layers of collected contaminants will effectively insulate the collector plates from the airstream and the air cleaner will no longer be effective. In that event, it is necessary to clean the electronic cells. In some cases, the smaller cells can be washed in a dishwasher. Since the effectiveness of the dishwasher in rising itself of all the contaminants from cleaning the electronic cell is not known, it may not be advisable to use the same dishwasher used for the kitchen dishes. In an industrial setting, it is prudent to treat the air cleaner cell as industrial equipment as described below.
How often should I wash electronic air cleaner cells?
There is no universally applicable answer to this question. Like so many things, your cell cleaning requirements will vary with the application of the air cleaner and the condition of the workplace atmosphere. When used for mineral oil coolant mist, vertical airflow air cleaners are largely self-cleaning as the collected mineral oil mist drips off the collector plates back into the machine tool. In mineral oil applications, cleaning may not be necessary for a month or two, or even longer.
For water-soluble coolant applications, a mixture of coolant and tramp oil (e.g., from way lube) may accumulate on the collector section and it may require cleaning every few week or months. When operating in thick smoke or a dusty atmosphere it may be necessary to wash the cells twice a week. In short, if it’s no longer cleaning, it’s time to wash the cell.
Cleaning the electronic cell
When handling the cell, avoid grabbing the cell by the ionizing grid or the collector plates. This can distort the plates and lead to arcing. Also avoid handling the cell by the contacts. Use the handle for removing and re-installing the cell and for handling the cell during cleaning. The cell can also be handled by grasping the frame/chassis. Be aware that there may be sharp edges on the sheet aluminum chassis. We recommend wearing gloves to protect against cuts.
Slight kinks in the collector plates can be straightened out with flat nose (“duckbill”) pliers.
Be careful to avoid accidentally dislodging the ionizer wires. If ionizer wires are dislodged and lost, replacements are available from the manufacturer.
To ensure good electrical contact, wipe the contact plates in the air cleaner chassis and the bare unpainted area on the tracks that hold the cell.
While the cell is out of the air cleaner, take the opportunity to inspect the contact plates in the cabinet. Look for possible distortion or signs of arcing. If the contacts appear “flattened” they can be bent back out with hand pressure or a pair of pliers.
Use aluminum-safe alkaline detergent when cleaning the cell. Although there may be variations between air cleaner manufacturers, the below instructions for using Air Quality Engineering PN 45036 Cell Cleaner concentrate are representative of many detergents:
Pour six (6) gallons of hot water into an appropriately sized container and add ½ gallon of cell cleaner concentrate.
Immerse the cell in the solution and allow the cell to sit for 1 -2 minutes.
Remove the cell and thoroughly rinse with hot water. Soaking the cells in clean hot rinse water for a few minutes is recommended.
Avoid using a pressure-washer to clean or rinse the cells. The high velocity jet of water can dislodge the ionizer wires and may distort the collector plates.
If the cell remains dirty, repeat the steps above until the cell is clean.
The cell can be immediately re-installed. It may snap for few minutes until the airflow through the air cleaner dries the cell out.
Count the ionizer wires before re-installing to be sure that no wires have become dislodged. There should be 9 wires per cell.
Metal mesh pre-filters can be cleaned with compressed air or a water jet followed by cleaning in the same solution used for cleaning the electronic cells. They should, however, be cleaned AFTER the electronic cells. This is because possible lint residue from the prefilters may contaminate the wash water and deposit on the cells.
When replacing the electronic cell be sure that the arrow embossed on the end of the cell points in the direction of air flow (ionizer wires should be on the “upstream” side).
Safety tips when cleaning the cells
Industrial alkaline detergents can cause eye and skin irritation, so we recommend following these precautions:
Do not splash the cleaning solution in your eyes. Wear chemical goggles to protect your eyes.
Avoid prolonged contact with your skin. Wear chemical-resistant gloves.
Wear glove to protect against cuts from sharp sheet metal edges.
Keep the detergent out of reach of children.
If you have any questions on cleaning the cells of your electronic air cleaner, or are looking for a new electronic air cleaner for your environment, please give Air Quality Engineering a call.